Terminology

2205 terms, tools, patterns and metrics an architect is expected to use precisely. Each one gets a short explanation of what it is, and — where it matters — what it is commonly confused with. Search filters as you type; the column headers sort.

All areas2205 Architecture Fundamentals77 Distributed Systems107 Data Architecture110 Cloud Architecture94 Networking88 API & Integration Architecture82 Reliability & Resilience75 Observability70 Performance & Capacity Engineering72 Security Architecture86 Cost Architecture & FinOps71 Business Architecture67 Architecture Communication67 Enterprise Architecture66 Legacy Modernization71 AI-Era Architecture69 Software Architecture & Engineering71 Architecture Patterns71 Architecture Decision-Making63 The Architect's Meta-Skills61 Delivery & Release Engineering66 Platform Engineering & Developer Experience70 Testing & Quality Architecture66 Data Platform Architecture64 Streaming & Real-Time Data69 Data Governance & Semantics69 Frontend & Experience Architecture66 Edge, Mobile & IoT68 Regulatory & Data Protection Architecture65 Assurance, Audit & Model Risk64

Kind Any concept794 practice734 pattern368 metric125 case-study77 tool62 protocol45

2205 terms shown.

Term	Kind	Topic	What it is
Retryable Error	concept	API Error Handling	An error whose cause may resolve on its own, which a client may safely attempt again — as distinct from one that will fail identically.
Reverse Compatibility Window Revert Window, Rollback Precondition	concept	Rollback & Forward Fix	The period during which every live consumer must still accept the previous version's output, because a rollback of one component is a forward-incompatible change for everything downstream of it.
Reverse ETL Operational Analytics, Data Activation	pattern	Reverse ETL	Pushing modelled data from the warehouse back into operational systems so that business tools act on the same definitions analysts report on.
Reverse Proxy	pattern	Networking	A server that receives client requests on behalf of one or more backends, forwarding them and returning the response.
Reverse Proxy in Practice	pattern	Reverse Proxies	A server that sits in front of origins and terminates, caches, routes and protects — the cheapest place to solve several problems at once.
Reverse Replication Cutover Backflow Replication, Bidirectional Cutover Window, Rollback Stream	pattern	Coexistence Patterns	Keeping a replication stream flowing from the new store back to the old one after writes have moved, so that rolling back stays a routing change instead of a restore from backup.
Reversibility	concept	Trade-off Fundamentals	The property of a decision that determines how much analysis it deserves, since a cheaply reversible choice can be tested rather than debated.
Reversible Decision Two-Way Door	concept	Architecture Decision-Making	A choice that can be undone cheaply, and which therefore deserves far less deliberation than an irreversible one.
Review Latency	metric	Code Review	The time between a change being ready for review and the review happening, which is usually the largest component of lead time.
Review Readiness Criteria	practice	Architecture Reviews	A stated bar a design must meet before review, so the session is spent on judgement rather than on discovering that the work is not ready.
Review Scope Discipline	practice	Design Authority	Stating what an architecture board does not review, which is what determines whether it stays useful or becomes a queue.
Review Scope Mismatch Blast-Radius Blindness in Review, Scope-Blind Approval	concept	Systems Thinking	A control that inspects the mechanics of a change while the risk lives in its reach - so the review passes honestly and the change still destroys something.
Reviewer Throughput Ceiling Oversight Capacity Limit, Review Time Budget	metric	Human-in-the-Loop Design	The number of items a human reviewer can genuinely assess per hour, which bounds what any human-in-the-loop control can actually deliver regardless of what the design document claims.
Revisit Condition Decision Expiry, Reconsider Trigger	practice	Writing Decision Records	The stated, checkable circumstance under which an architectural decision should be reconsidered - the field that turns a historical record into a live decision.
Revocation Path Fast-Propagation Channel, Fail-Closed Config	pattern	Cloud Governance	A separate, short-TTL, fail-closed channel for security-critical configuration changes, coexisting with an eventually-consistent cached channel for ordinary configuration.
Revocation Window Token Lifetime as SLA, Local Validation Trade	concept	Tokens & JWTs	The period during which a revoked credential remains accepted, which for locally-validated tokens is exactly the token lifetime - the unavoidable price of removing the identity provider from the request path.
Right to Erasure Right to be Forgotten	concept	Erasure vs Immutability	An individual's right to have their personal data deleted, which collides directly with append-only and immutable architectures.
Rightsizing	practice	Rightsizing	Matching provisioned resources to measured need — the fastest large cost reduction available, and one that must respect headroom requirements.
Risk Appetite	concept	Risk Appetite	The amount and type of risk an organisation is willing to accept in pursuit of its objectives, stated explicitly enough to guide a design decision.
Risk Assessment Methods	practice	Risk Assessment Methods	Structured ways to identify and prioritise what could go wrong — where the value is the conversation and the ranking, not the number.
Risk Tolerance Statement	concept	Risk Appetite	The board-level declaration of how much of each risk type the organisation will accept, which is what tells an architect which risks may be accepted without escalation.
Roadmapping	practice	Architecture Roadmaps	Sequencing architectural change so that each step delivers value and is safe to stop after — rather than planning a destination nobody reaches.
Roblox 2021: A Coordination Layer as a Single Point of Failure Roblox 73-Hour Outage	case-study	Service Discovery	A performance problem in the shared service-discovery cluster took the entire platform down for 73 hours, and its novelty made it extremely difficult to diagnose.
Role Explosion	concept	Authorization	The proliferation of narrowly-scoped roles that occurs when RBAC is used to express rules that actually depend on context.
Rolling Update Surge	concept	Deployment Strategies	The extra capacity a rolling deployment temporarily adds, and the unavailability it is permitted, which together decide whether the rollout is safe under load.
Rollup Policy Pre-Aggregation Policy, Retention Tiering	practice	Real-Time Analytical Stores	The decision - made before ingestion, not after - about what granularity of data is retained for how long, and at what point raw events are collapsed into aggregates.
Round-Trip Time RTT, Latency Floor	metric	Network Performance	The time for a packet to travel to a destination and back — a physical floor that no application optimisation can reduce.
Route Origin Validation ROV, RPKI Origin Validation	practice	Routing & BGP	Checking a BGP announcement's origin against a signed authorisation before accepting it, so a more specific prefix announced by the wrong network is dropped instead of winning.
Route Propagation	concept	Routing & BGP	Automatically inserting routes learned from a VPN or dedicated connection into a route table, rather than maintaining them by hand.
Route Table	concept	Subnetting	The set of rules deciding where traffic leaving a subnet is sent, and the thing that actually makes a subnet public or private.
Row Group Sizing Row Group Tuning, Parquet Block Size	practice	File Formats & Compaction	Choosing how many rows a columnar file groups into one statistics-bearing unit, which sets both the finest granularity a query can skip and the memory a writer and reader need.
Row-Level Security RLS, Fine-Grained Access Control	pattern	Row & Column-Level Security	Access control enforced by the data platform on which rows a given principal can see, rather than by each application or query.
RTO and RPO	metric	RTO & RPO	How long recovery may take, and how much data may be lost — the two numbers from which every disaster recovery design follows.
RTO and RPO Recovery Time Objective, Recovery Point Objective	metric	Reliability & Resilience	How long recovery may take (RTO) and how much data may be lost (RPO), the two numbers that determine the cost of a resilience design.
Rule of Three Abstract at the Third Instance, Duplicate Before Abstracting	practice	Evolutionary Architecture	Hard-code the first case, copy for the second, abstract at the third - because only the third instance reveals which parts actually vary.
Runbook Playbook	practice	Observability	A short, actionable document telling an on-call engineer what an alert means, what to check, and what the safe mitigations are.
Runbook Quality	practice	Incident Management	The properties that make an operational procedure usable by a tired responder under pressure, as opposed to a document that merely exists.
Runtime Compliance Drift Plan-Time Blind Spot, Post-Apply Divergence	concept	Architecture Compliance Checks	The growing gap between what infrastructure code declares and what the running estate actually looks like, which a pipeline-based policy check cannot see and therefore reports as compliant.
Runtime Composition	pattern	Micro-Frontends	Assembling one page from independently deployed fragments at request or render time, which is what makes micro-frontends more than separate builds.
Runtime Composition Risk Remote Module Risk, Deferred Integration Failure	concept	Module Federation	The class of failures created by resolving module existence, export shape and shared-dependency versions in the user's browser instead of at build time - including the inability to roll back a remote you do not own.
Saga Compensating Transaction, Long-Running Transaction	pattern	Distributed Transactions	A sequence of local transactions across services where failure is handled by compensating actions rather than by rollback.
Saga	pattern	Distributed Systems	A sequence of local transactions across services where each step has a compensating action that semantically undoes it if a later step fails.
Saga Compensation Design	practice	Saga	Designing the undo actions for a distributed transaction, where compensation is a new business action rather than a rollback.
Saga Isolation Anomaly	concept	Saga	The intermediate states visible to other transactions during a saga, because a saga provides atomicity and durability but not isolation.
Saga Orchestrator	pattern	Sagas & Compensation	A component that explicitly drives a saga's steps and compensations, holding the flow in one place rather than distributing it across event subscriptions.
Salesforce's Metadata-Driven Multi-Tenancy	case-study	Data Architecture	Salesforce serves every customer from shared infrastructure with a single physical schema, storing customer-specific data structures as metadata rather than as separate tables.
Sampling Risk Detection Probability, Audit Sampling Power	metric	Continuous Controls Monitoring	The probability that a sample-based control test misses a violation that exists in the population - which for small samples and rare violations is most of the time.
Saturation Point	concept	Throughput	The load level beyond which additional demand produces queueing and latency growth rather than additional completed work.
Scalability	concept	Distributed Systems	The ability to handle growing load by adding resources, ideally with cost rising no faster than the load.
Scale Cube	concept	Horizontal vs Vertical Scaling	A model describing three independent axes of scaling — cloning, functional decomposition, and data partitioning — each addressing a different limit.
Scanned Bytes	metric	Analytics Cost Control	The volume a query reads, which is what most analytical engines bill for and what almost every optimisation ultimately reduces.
Scenario-Based Comparison Concrete Scenario Evaluation, Cash Out the Qualities	practice	Trade-off Analysis Methods	Comparing design options against specific described situations rather than against abstract qualities - which forces vague terms to be cashed out and turns a discussion into a decision.
Scheduled Capacity Predictive Provisioning, Calendar-Driven Scaling	practice	Autoscaling	Provisioning ahead of a known event rather than reacting to its traffic - the correct primary control for any spike whose rise time is shorter than an autoscaler's reaction time.
Scheduler Control Plane	concept	Workflow Schedulers	The orchestrator's own state and availability, which becomes a critical dependency for every pipeline it runs.
Schema Compatibility Mode	concept	Streaming Schema Evolution	The rule stating which schema changes a registry will accept, which encodes whether producers or consumers are expected to upgrade first.
Schema Evolution	concept	Data Lakes & Lakehouses	Changing a table's structure over time while keeping existing data readable and existing consumers working.
Schema Registry	tool	Schema Registry	A central service holding message schemas with enforced compatibility rules, so a producer cannot publish a change that breaks its consumers.
Scope Reduction	practice	PCI-DSS Scoping	Shrinking the set of systems that store, process or transmit cardholder data, because the cost of the standard is proportional to the number of systems in scope.
Screen Shaped Endpoint	pattern	BFF for Experience	An endpoint that returns exactly what one screen needs in one request, shaped by the interface rather than by the domain model.
Screening Enforcement Point Sanctions Control Placement, Party Screening Gate	pattern	Geo-Restriction & Sanctions	The place in a system where a restriction is actually enforced - which must match what the obligation is about, since sanctions apply to parties and licensing restrictions apply to locations, and a control pla…